Hydroacoustic drive mechanism having a flexural seal

ABSTRACT

A HYDROACOUSTIC TRANSDUCER IS DESCRIBED HAVING A RADIATOR IN THE FORM OF A FLEXING DISC AND AN ACOUSTIC DRIVE MEMBER FOR COUPLING A FLUID-FILLED CAVITY, THE PRESSURIZED FLUID IN WHICH IS ACOUSTICALLY MODULATED, TO THE RADIATOR. THE DRIVE MECHANISM INCLUDES A PISTON WHICH IS GUIDED IN AN OPENING IN THE HOUSING WHICH EXTENDS INTO THE CAVITY CONTAINING THE PRESSURE-MODULATED FLUID. AN ANNULAR-SEAL IS PROVIDED IN THE OPENING AND EXTENDS PARTIALLY INTO THE PISTON AND INTO THE WALL OF THE OPENING. THE WALL OF THE OPENING AND THE PISTON IS CONSTRUCTED TO PROVIDE A CLAMPING STRUCTURE SO THAT FLUID IS PREVENTED FROM LEAVING THE CAVITY WHILE THE PISTON IS PERMITTED TO VIBRATE IN RESPONSE TO THE ACOSTIC ENERGY OF THE MODULATED FLUID.

United States Patent [45] Patented [73] Assignee June 28, 1971 General Dynamics Corporation [54] HYDROACOUSTIC DRIVE MECHANISM HAVING A FLEXURAL SEAL 8 Claims, 3 Drawing Figs.

[52] US. Cl 116/137, 74/18.2,181/0.5, 251/335, 340/15 [51] Int. Cl Gl0k 9/00 [50] Field of Search 116/27, 70,

137, 137 (A); 181/0.5, 5 (H), 5 (EM), 31, 32; 74/18.2;340/8, 10,12,l5;251/335.1; 103/150; 92/249, 93, 137, 98, 93; 417/(Inquired); 73/406;

2,444,049 6/1948 King 340/8 2,587,848 3/1952 Horsley et a1 116/137 2,757,898 8/1956 Cox 251/335.1X 2,896,987 7/1959 Meyer 74/182 3,056,104 9/1962 De Kanhski et al. 340/5 3,143,999 8/1964 Bouyoucos 116/137 3,174,129 3/1965 Laughlin et a1. 340/5 3,212,473 10/1965 Bouyoucos 116/137 3,382,841 5/1968 Bouyoucos 116/137 Primary Examiner-Louis J. Capozi Attorney-Martin Lu Kacher ABSTRACT: A hydroacoustic transducer is described having a radiator in the form of a flexing disc and an acoustic drive member for coupling a fluid-filled cavity, the pressurized fluid in which is acoustically modulated, to the radiator. The drive mechanism includes a piston which is guided in an opening in the housing which extends into the cavity containing the pressure-modulated fluid. An annular seal is provided in the opening and extends partially into the piston and into the wall of the opening. The wall of the opening and the piston is constructed to provide a clamping structure so that fluid is prevented from leaving the cavity while the piston is permitted to vibrate in response to the acoustic energy of the modulated fluid.

PATENTEnJuuzalsn 3.587.519

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IIYDROACOUSTIC DRIVE MECHANISM HAVING A FLEXURAL SEAL The present invention relates to the acoustic drive mechanism, and particularly to a hydroacoustic transducer having an improved acoustic drive mechanism.

The invention is especially suitable for use in hydroacoustic transducers having a cavity for containing pressurized fluid in which a high amplitude acoustic energy is generated, and also having a radiator which is air-backed. The invention provides an acoustic drive mechanism for coupling acoustic energy from the cavity to the radiator, while preventing the fluid from entering the air-filled space backing the radiator.

It has been found that a conventional seal, such as O-rings,

V are not operative toprevent leakage from a high-pressure region to a low-pressure region as may exist in high-power hydroacoustic transducers. Either the seal precludes the proper operation of the drive mechanism which couples the energy from the high-pressure region to the ambient, or is not effective to prevent the high-pressure acoustically modulated fluid from leaving the high-pressure region and entering the ambient or space within the transducer, as for example the space which contains air for backing a radiator. By virtue of such leakage, proper operation of the hydroacoustic transducer was prevented because the leakage of fluid changes the acoustic characteristics of the transducer.

It is therefore an object of the present invention to provide improved apparatus for transferring acoustic energy from a fluid to a load.

It is a still further object of the present invention to provide an improved acoustic drive mechanism.

It is a still further object of the present invention to provide an improved hydroacoustic transducer.

Briefly described, an acoustic drive mechanism embodying the invention utilizes the housing of a transducer in which pressurized and acoustically modulated fluid is generated. The housing has an opening which communicates with a cavity containing the modulated fluid. A piston is disposed in the opening. Thewall in the opening may be defined by a guide plate and by another plate apertured for receiving and guiding the piston. At least one of the plates is notched to define an annular slot when the plates'are disposed in side by side relationship. The piston may also be a bipart structure. One or both parts of the piston are notched along an edge thereof at its outer periphery so as to define another annular slot. An annular flexural seal is disposed within these slots and encompasses the piston. The plates and the parts of the piston are fastened together to provide axial clamping pressure upon the portions of the seal extending therein. The seal permits the piston to vibrate under the influence of the modulated fluid in the cavity while preventing the escape of the fluid from the cavity. The opposite end ofthe piston may be connected to a radiator of the hydroacoustic transducer and drives the radiator to project acoustic energy which is generated in the chamber in the housing.

The invention itself, both as to its organization and method of operation, as well as additional objects and advantages thereof will become more readily apparent from a reading of the following description in connection with the accompanying drawings in which:

FIG. 1 is a sectional view schematically showing a hydroacoustic transducer embodying the invention;

FIG. 2 is a fragmentary sectional view, the section being taken along the lines 2-2 in FIG. 1 and showing the portion of the transducer containing the acoustic drive mechanism in greater detail; and

FIG. 3 is a fragmentary sectional view taken along the line 3-3 in FIG. 2.

Referring more particularly to FIG. 1, there is shown a sectional view along a plane extending through the axis of the hydroacoustic transducer. The transducer has a housing 10, a radiator 12, which is mounted on the housing, a spool valve 14, which is vibrated by an electromechanical driver 16, and an acoustic drive mechanism 18, which is coupled to the radiator I2. The hydroacoustic energy generated within the housing 10 is translated into acoustic vibration of the radiator 12. The fastening elements, such as bolts, which connect the radiator to the housing and other elements of the transducer assembly together are not shown in FIG. 1 to simplify the illustration.

The housing has several cavities or chambers'therein which play a part in the generation of the hydroacoustic energy. Fluid, such as hydraulic oil, enters the housing via a supply line 20 into a supply port cavity 22, and thence flows into a port structure defined by the walls of a bore 24 in which the spool valve 14 vibrates. A pair of chambers 26 and 28 are located at the ends of the bore and contain the pressurized fluid which serves to center the spool valve within the port structure. The orifices of the valve are defined by a slot 30 which intersects the bore 24. This slot 30 opens into an output cavity or chamber 32 and a shunt cavity 34. The electromechanical driver 16 is disposed in the cavity 28. It includes an electromagnetic or electrostrictive element which is energized by alternating current electrical signals applied across the terminal 36 and 38. The driver 16 has an end cap 40 attached to the element. The end cap therefor is vibrated within the cavity 28 when the driver is energized with AC voltage. The motion of the end cap is translated via the fluid in the region of the cavity 28 and the bore 24 between the end cap 40 and the end of the spool valve 14 opposite thereto, so as to vibrate the spool valve. The flow of the pressurized fluid is therefore from the supply port 20 and its cavity 22, through the port structure, the cavities 32 and 34 and to a return line 42 via a return port cavity 44. The pressure in the output cavity 32 of the pressurized fluid contained therein, is therefore modulated in accordance with the electrical signals applied to W the driver 16. Since the pressure of the fluid may be very high, say 6,000 p.s.i., the acoustic energy in the pressurized fluid in the cavity 32 is of extremely high magnitude.

It is difficult problem to translate this acoustic energy into acoustic vibration of the radiator 12 without any leakage of the highly pressurized fluid from the output cavity 32, particularly into the air or other gas in the region 76 backing the radiator 12. The acoustic driver mechanism 18 accomplishes such translation of energy without introducing any such leakage.

The radiator 12 is a flexural disc which is connected via a ring section 46 to the housing 10. The thickness of the radiator may for example be about 2 inches at the thinnest portion thereof (measured along the axis of the device). Thus, the radiator must be flexed by relatively high force over a relatively long distance, say 0.0l inch. The drive mechanism utilizes a piston 48 which is coupled to the disc 12, and at the opposite face thereof extends into the cavity 32. An annular seal 50 which extends partially into the piston 48 and partially into the housing 10' permits the requisite movement of the piston without introducing any leakage of the high-pressure fluid from the output cavity 32. Clamping means contained in the piston 48 and in the housing 10 are included in the drive mechanism for applying axial pressure on the seal 50 which restrains it within the housing and the piston and yet permits the piston 48 to vibrate, as required.

The drive mechanism 18 is shown in greater detail in FIGS. 2 and 3. The piston 48 has two parts 52 and 54. These parts have stepped abutting end surfaces which are notched so as to define a slot 56 in which the seal 50 extends. An O-ring 58 may be disposed between the abutting surfaces of the piston parts 52 and 54 so as to insure that there is no possible leakage therethrough. This O-ring 58 would alone not be sufficient to preclude leakage of the high-pressure fluid from the cavity 32, if an O-ring were disposed between the wall of the piston and its adjoining wall. A plurality of screws 60 (three being shown) join the piston parts 52 and 54 and apply axially directed clamping forces upon the portion of the annular seal 50 which extends into the piston 48. The piston is connected to the radiator 12 by means of a bolt 62.

The housing I0 has an opening therein in which the piston 48 is movably disposed. This opening is defined by a pair of plate members 64 and 66. One of these plates serves as a guide plate which defines the walls of the opening in which the piston 48 is movable. The other disc 66 is a clamping disc which abuts the guide plate disc 64 when the discs 64 and 66 are juxtaposed. The edges of the abutting surfaces of the discs 64 and 66 may be notched to define a slot 68 into which the portion of the annular flexural seal extends. The clamping plate 66 provides axial clamping pressure upon the flexural seal 50. This pressure is applied by means of a plurality of screws 70 (four being shown) which clamp the plates 64 and 66 together. O-rings 72 and 73 similar to the O-ring 58 may be provided to insure that there will be no possible leakage path from the cavity 32. The clamping plates 64 and 66 are connected to the housing 10 by a plurality of screws 74 (four being shown) which apply the necessary hold down forces and assist in applying the clamping forces upon the annular flexural seal 50.

The seal itself is a ring of polyurethane material. The type of polyurethane which is sold by the Disogren Company, Manchester, N.H. is suitable. The seal should encompass the piston and substantially fill the slots 56 and 68. A thickness of the seal (in the axial direction) of 0.100 inch is desirable in order to provide sufficient structural strength and yet allow for vibratory movement.

The space 76 (viz. the air backing for the radiator 12) is air filled and will be at a much much lower pressure than the fluid-filled cavity 32. The fluctural seal 50, while permitting motion of the piston 48 and corresponding motion of the radiator 12, precludes the leakage of any fluid into this low pressure space 76.

From the foregoing description, it will be apparent that there has been provided an improved hydroacoustic transducer, and particularly an improved drive mechanism for coupling a high-pressure region, in which vibratory energy is generated, to an output load device without introducing leakage or other adverse effects. The operation of hydroacoustic transducers has not been described in detail in order to simplify the illustration. Reference may be had to US. Pat. No. 3,212,473, issued Oct. 19, 1965 to John V. Bouyoucos for further infonnation respecting such transducers. Variations and modifications of the herein described apparatus within the scope of the invention will undoubtedly suggest themselves to those skilled in the art. Accordingly, the foregoing description should be taken as illustrative and not in any limiting sense.

lclaim:

1. Apparatus for transferring vibratory energy to a load which comprises a. means for providing a pressure-modulated fluid including a housing having a chamber for confining said pressuremodulated fluid,

b. said housing having an opening extending between said chamber and said load,

c. a piston coupled to said load and movably disposed in said opening, an end face of said piston being exposed to said pressure-modulated fluid in said chamber,

d. a flexural seal encompassing said piston, said seal extending radially inwardly into said piston and radially outwardly into said housing, and

. means included in both said piston and said housing for clamping the portions of said seal extending inwardly into said piston and outwardly into said housing so as to permit said piston to vibrate axially within said opening in response to said modulated fluid in said chamber without leakage of fluid out of said chamber. 2. The invention as set forth in claim 1 wherein said flexural seal is annular in shape.

3. The invention as set forth in claim 2 wherein said seal is of polyurethene material.

4. The invention as set forth in claim 2 wherein said seal has a rectangular cross section in its unclamped state.

5. The invention as set forth in claim 1 wherein said clamping means includes a ortion dis sed in said housing comprising a pair of plates isposed si e by side in abutting rela ionship, said plates having said opening extending therethrough, the abutting sides of said plates of said opening defining an annular slot for receiving and clamping the portion of said seal which extends outwardly into said housing, said clamping means for said piston including a bipart structure, the abutting sides of the parts of said structure defining a slot along the peripheral edge thereof for receiving and clamping the portion of said annular seal which extends inwardly of said piston.

6. In a hydroacoustic transducer having a housing, a chamber in said housing and means for providing a pressuremodulated fluid in said chamber, the combination comprising a radiator for acoustic energy corresponding to the modulation of said fluid, said radiator including a flexural member and means supporting said member on said housing so as to define a volume between said housing and said radiator, said housing having an opening extending between said space and said chamber, a piston axially movable within said opening with the walls of said piston and the wall of said housing being substantially adjacent and coupled to said radiator, an annular flexural seal extending between the adjacent walls of said piston and said housing opening and extending inwardly into said piston and outwardly into said housing, and means in said piston and said housing for applying clamping pressure in a direction axially of said piston circumferentially upon the portions of said seal which extend outwardly into said housing and inwardly into said piston whereby to prevent leakage between said chamber and said volume and allowing said piston to vibrate axially whereby to translate the modulation of said fluid in said chamber into acoustic vibration of said radiator.

7. The invention as set forth in claim 6 wherein said piston is divided into two parts, which abut each other in end to end relationship so that the abutting parts forming a slot at the outer periphery thereof for receiving and clamping the portion of said annular seal extending radially inwardly into said piston, and a plurality of screws extending axially through said abutting parts of said piston for fastening said parts together and applying said clamping pressure upon said seal.

8. The invention as set forth in claim 7 wherein said means in said housing for applying clamping pressure upon said seal comprises a pair of plates which abut each other in side by side relationship, an opening through said plate forming said opening for said piston, an edge of at least one of said plates at the abutting sides thereof along said opening being notched to form a slot for receiving said seal, and a plurality of screws extending axially through said plates for applying said clamping pressure upon said seal, and means for attaching said clamped abutting plates to said housing. 

